Diluting Flux Paste with Isopropyl Alcohol

Discussion in 'General Electronics Chat' started by TeraBeam, Jun 26, 2013.

  1. TeraBeam

    Thread Starter New Member

    Jun 26, 2013
    I am wondering if anyone has any experience with diluting flux paste into a less viscous form using isopropyl alcohol. I am waiting for a shipment of liquid flux currently and was just curious if this is a feasible hold-over.

    It's my understanding that generally flux is just 25-85% rosin dissolved in 75-15% isopropyl alcohol, but I could certainly be mistaken.

    Specifically, I have MG Chemicals No Clean Flux Paste in syringe form catalog #8341-10ML and I am using 70% isopropyl. Currently I get the correct viscosity at around 1 part paste to 6 parts alcohol. I've tested and the flux still seems to do its job in this form, but it would be great to hear from someone who is more knowledgeable on this subject.
  2. SgtWookie


    Jul 17, 2007
    I've used isopropyl alcohol to thin rosin flux, but I use 90% or better. I suggest NOT using the 70%, as it is 30% water which can cause a variety of problems; one not being able to melt solder um til the water boils off. Wal-Mart carries large bottles of 90% isopropyl in the health section.
    TeraBeam and Bernard like this.
  3. Brainbox


    Nov 15, 2010
    I have used isopropyl before to thin flux, found no problems with that.
    Yet I use denaturalized ethyl alcohol of 96% because it is much cheaper by the volume of 1 liter.
    I use it also to clean the boards after soldering to remove the residu.
    It takes some more time to vaporize then isopropyl but thats is not a big isue to me.
    TeraBeam likes this.
  4. TeraBeam

    Thread Starter New Member

    Jun 26, 2013
    I just wanted to say that the solution of using 90% Isopropyl to thin out flux paste worked very well for me in a pinch. Thank you to both SgtWookie and Brainbox for the advice!
  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Be very careful with 90% isopropanol (IPA) around heat sources and sparks.
    Close the cap, keep the bottle away from the soldering iron. Even the flux solution in isopropanol. The IPA vapors settle on your bench top and can combust.

    In graduate school, a lab mate was trying to dissolve some formulation in IPA and set it on a magnetic stirring plate to mix. About 3 minutes latter, there was a flash fire that started on the bench top (likely ignited by the stirrer) and, after a second, the fire followed the vapor trail onto the floor and burned for about 3 second. The paper towels overflowing in the garbage can started burning a few seconds later.

    All was fine - no major damage and nobody was injured, just be careful.